The present invention is directed to a technique capable of converting document data into image data constituted by a plurality of pixel data, in particular, CMYK image data corresponding to a format suitable for printing operation. The document data is constituted by containing a draw command used to designate a draw object of draw data such as a text and a figure, and of image data such as a photograph.
Conventionally, while using a printer driver constituted on a computer, a data conversion operation from document data into CMYK image data suitably formatted to a printing operation is carried out as follow. This document data is constituted by containing a draw command used to designate a draw object.
In this data converting operation, draw commands contained in document data sent from an application program are stored into a spooler formed on a memory in accordance with a drawing order. Next, the draw commands stored in the spooler are read out in the drawing order, and then draw objects specified by these read draw commands are image-expanded so as to obtain RGB image data. Thereafter, the RGB image data thus obtained is subjected to color-correction with reference to a color conversion table for storing thereinto color correction information and the like, so as to be converted into desirable CMYK image data.
On the other hand, normally, there is a difference between a color correction required when a draw object corresponds to draw data and another color correction required when this draw object corresponds to image data. Concretely speaking, in the case that a draw object designated by a draw command contained in document data corresponds to such draw data as a text and a figure, one color correction should be applied when RGB image data obtained from this document data is converted into CMYK image data. In the case that the above-described draw object corresponds to such image data as a photograph, another color correction should be applied when RGB image data obtained from this document data is converted into CMYK image data. In these color corrections, for instance, this image data is required to be color-matched with a monitor, whereas a saturation of the draw data constitutes a major important factor.
As a consequence, in a conventional image conversion system, two different sorts of color conversion tables are prepared for draw data and image data. Prior to a printing operation, a user is requested to select a sort of document data to be printed out (namely, user selects printing operation of draw data or image data). Then, RGB image data is converted into CMYK image data by employing a color conversion table in accordance with the selected data.